Pump device and outboard motor

ABSTRACT

The disclosure provides a pump device and an outboard motor equipped with the same. The pump device to be applied to an outboard motor includes a housing that has an insertion hole into which a drive shaft driven by an engine is to be inserted; and a resin cover member that is fixed to the housing to cover an outer wall surface of the housing in a region having the insertion hole. The cover member has a small-diameter insertion hole having an inner diameter smaller than the insertion hole to allow the drive shaft to be rotatably inserted thereto.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefits of Japanese application no. 2022-052778, filed on Mar. 29, 2022. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND Technical Field

The disclosure relates to a pump device to be applied to a lubrication system of an engine such as an outboard motor, and more particular to a pump device to be disposed in a region where a crankshaft of the engine and a drive shaft of a propeller are connected, and an outboard motor including the same.

Related Art

A conventional outboard motor is known to have an engine, a body (housing), a propeller, a drive shaft connected to a crankshaft of an engine to drive the propeller, and an oil pump and the like disposed in a region where the drive shaft is connected to the crankshaft and is fixed to a lower end of the engine (e.g. Patent Literature 1).

In this outboard motor, although the drive shaft is inserted into the oil pump and connected to the crankshaft, and the drive shaft is disposed in the body, it is disposed in a region of seawater atmosphere exposed to seawater.

As a result, seawater or seawater droplets and the like guided along the drive shaft may intrude through an opening of the oil pump to the inside and cause functional failure due to salt damage. Moreover, since a lower surface of the oil pump is exposed, there is also a risk of surface corrosion rust and the like due to salt damage.

Another outboard motor is known to have an engine, a body (housing), a propeller, a drive shaft connected to a crankshaft of an engine to drive the propeller, and an oil pump and the like disposed in a region where the drive shaft is connected to the crankshaft and fixed to a lower end of the engine, and include a sealing material inside the oil pump for liquid-tightly sealing around the drive shaft (e.g. Patent Literature 2).

In this outboard motor, when seawater droplets or seawater and the like guided along the drive shaft intrudes from an opening of an oil pump to the inside and reaches the sealing material, further intrusion is suppressed, but there is still a risk of causing a functional failure due to salt damage inside the oil pump. Moreover, since a lower surface of the oil pump is exposed, there is also a risk of surface corrosion, rust and the like due to salt damage.

CITATION LIST Patent Literature

-   [Patent Literature 1] JP 3042013 -   [Patent Literature 2] JP 2001-82124

The disclosure provides a pump device and an outboard motor including the same capable of preventing salt damage and ensuring functional reliability while reducing costs and simplifying the structure without performing expensive rust prevention treatment.

SUMMARY

A pump device of the disclosure is one to be applied to an outboard motor, including a housing that has an insertion hole into which a drive shaft driven by an engine is to be inserted; and a resin cover member that is fixed to the housing to cover an outer wall surface of the housing in a region having the insertion hole. The cover member has a small-diameter insertion hole having an inner diameter smaller than the insertion hole to allow the drive shaft to be rotatably inserted thereto.

An outboard motor is configured to be one including: an engine body, a crankshaft that extends vertically in the engine body; an oil pan fixed to the engine body and storing oil, and a pump device fixed to the engine body and circulating the oil; a body that holds the engine; a drive shaft that is connected to the crankshaft and that rotates around an axis extending vertically; and a propeller rotated by the drive shaft. The pump device is one having any one of the above configurations.

With the pump device configured as such, it is possible to achieve cost reduction, simplification of structure, and the like without performing expensive rust prevention treatment, prevent salt damage and the like, and ensure functional reliability. Moreover, an outboard motor including the pump device can prevent salt damage and ensure functional reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing an outboard motor to which a pump device of the disclosure is applied.

FIG. 2 is an external perspective view of a pump device according to an embodiment of the disclosure viewed obliquely from above.

FIG. 3 is an external perspective view of a pump device according to an embodiment of the disclosure, viewed obliquely from below.

FIG. 4 is an exploded perspective view of a pump device according to an embodiment, viewed obliquely from above.

FIG. 5 is an exploded perspective view of a pump device according to an embodiment, viewed obliquely from below.

FIG. 6 is a partial cross-sectional view showing an interrelationship between a pump device, a crankshaft and a drive shaft of an engine mounted on an outboard motor, and an oil pan according to an embodiment.

FIG. 7 is a perspective view of a housing body that constitutes a housing in a pump device according to an embodiment, viewed obliquely from above.

FIG. 8 is an external perspective view of a cover member according to a first embodiment as a cover member included in a pump device according to an embodiment, view obliquely from above.

FIG. 9 is a cross-sectional view of a cover member according to a first embodiment, taken along a vertical plane passing through an axis of a drive shaft included in an outboard motor.

FIG. 10 is a partially enlarged cross-sectional view showing a state in which a cover member according to a first embodiment is attached to a housing H (housing body 10) of a pump device applied to an outboard motor.

FIG. 11 is an external perspective view of a cover member according to a second embodiment, viewed obliquely from above.

FIG. 12 is a cross-sectional view of a cover member according to a second embodiment, taken along a vertical plane passing through an axis of a drive shaft included in an outboard motor.

FIG. 13 is a partially enlarged cross-sectional view showing a state in which a cover member according to a second embodiment is attached to a housing H (housing body 10) of a pump device applied to an outboard motor.

FIG. 14 is an external perspective view of a cover member according to a third embodiment, viewed obliquely from above.

FIG. 15 is a cross-sectional view of a cover member according to a third embodiment, taken along a vertical plane passing through an axis of a drive shaft included in an outboard motor.

FIG. 16 is a partially enlarged cross-sectional view showing a state in which a cover member according to a third embodiment is attached to a housing H (housing body 10) of a pump device applied to an outboard motor.

FIG. 17 is an external perspective view of a cover member according to a fourth embodiment, viewed obliquely from above.

FIG. 18 is a cross-sectional view of a cover member according to a fourth embodiment, taken along a vertical plane passing through an axis of a drive shaft included in an outboard motor.

FIG. 19 is a partially enlarged cross-sectional view showing a state in which a cover member according to a fourth embodiment is attached to a housing H (housing body 10) of a pump device applied to an outboard motor.

DESCRIPTION OF THE EMBODIMENTS

In the pump device, the housing may be configured to include a convex cylindrical portion that protrudes in an axial direction of the drive shaft to define a part of the insertion hole and the outer wall surface, and the cover member is formed to cover a region including the convex cylindrical portion.

In the pump device, the convex cylindrical portion of the housing may be configured to be a cylindrical portion that protrudes cylindrically around an axis of the drive shaft, and the cover member may include an annular flange portion in close contact with an outer wall surface around a root of the cylindrical portion, an outer peripheral wall portion that covers an outer peripheral surface of the cylindrical portion, and a bottom wall portion that covers an end surface of the cylindrical portion and defines a small-diameter insertion hole.

In the pump device, the convex cylindrical portion may be configured to be a cylindrical portion that protrudes cylindrically around an axis of the drive shaft, and the cover member may include an annular flange portion in close contact with an outer wall surface around a root of the cylindrical portion; an outer peripheral wall portion that covers an outer peripheral surface of the cylindrical portion; a bottom wall portion that covers an end surface of the cylindrical portion; and an inner cylindrical portion that extends from the bottom wall portion inward in the axial direction to be closely fitted to the insertion hole and defines a small-diameter insertion hole.

In the pump device, the convex cylindrical portion may be configured to be a cylindrical portion that protrudes cylindrically around an axis of the drive shaft, and the cover member may include an annular flange portion in close contact with an outer wall surface around a root of the cylindrical portion; an outer peripheral wall portion that covers an outer peripheral surface of the cylindrical portion; a bottom wall portion that covers an end surface of the cylindrical portion; and a tip cylindrical portion that extends from the bottom wall portion outward in the axial direction to define the small-diameter insertion hole.

In the pump device, the convex cylindrical portion may be configured to be a cylindrical portion that protrudes cylindrically around an axis of the drive shaft, and the cover member may include an annular flange portion in close contact with an outer wall surface around a root of the cylindrical portion; an outer peripheral wall portion that covers an outer peripheral surface of the cylindrical portion; a bottom wall portion that covers an end surface of the cylindrical portion; and a long cylindrical portion that extends from the bottom wall portion inward in the axial direction to be closely fitted to the insertion hole and extends outward in the axial direction to define the small-diameter insertion hole.

In the pump device, the inner cylindrical portion, the tip cylindrical portion, or the long cylindrical portion may be configured to include a spiral protruding portion formed spirally around the axis to define the small-diameter insertion hole.

In the pump device, the cover member may be configured to include, in the bottom wall portion, an annular protrusion portion that annularly abuts on the end surface of the cylindrical portion.

In the pump device, the cover member may be configure to include, in the outer peripheral wall portion, a plurality of linear protruding portions that extend in the axial direction to come into close contact with the outer peripheral surface of the cylindrical portion and arranged around the axis.

In the pump device, the plurality of linear protruding portions may configured to be formed to have a height dimension with which the cover member is press-fitted to the cylindrical portion of the housing.

In the pump device, a pump element housed in the housing is included, and the pump element may be configured to include an inner rotor connected to a crankshaft of the engine and driven to rotate, and an outer rotor interlocked with the inner rotor.

In the pump device, the housing may be configured to include an annular seal member disposed inside the cylindrical portion to be in close contact with an outer peripheral surface of the drive shaft inserted from the insertion hole and connected to the crankshaft.

In the pump device, the housing may be configured to include a second annular seal member disposed to come into close contact with an outer peripheral surface of the crankshaft in a region between the pump element and the annular seal member in the axial direction.

In the pump device, the housing may be configured to include an annular close contact region in which a flange portion of an oil pan is in annular close contact such that an outer wall surface outside a region covered by the cover member is arranged inside the oil pan included in the outboard motor.

Hereinafter, embodiments of the disclosure will be described with reference to attached drawings.

A pump device M according to an embodiment is applied to an internal combustion engine 1 mounted on an outboard motor A.

As shown in FIG. 1 , the outboard motor A includes the engine 1; a body 2 for holding the engine 1; a drive shaft 3 connected to a crankshaft 1 b of the engine 1 and extending in an axis S direction; a propeller 4 rotated via a transmission mechanism by the drive shaft 3; and a bracket 5 to be mounted on a hull.

Here, the crankshaft 1 b and the drive shaft 3 are positioned on an axis S extending vertically (up-down) in the outboard motor A.

The engine 1 includes an engine body 1 a, the crankshaft 1 b rotating around the axis S, an oil pan 1 c fixed to a lower end of the engine body 1 a to store oil, and the pump device M fixed to the lower end of the engine body 1 a, as shown in FIG. 1 .

In the outboard motor A, the pump device M is arranged such that most of a housing H is inside the oil pan 1 c, and a region connecting the drive shaft 3 is exposed to seawater atmosphere outside, as shown in FIG. 1 . The pump device M sucks up the oil in the oil pan 1 c via an oil strainer 1 d, discharges the pressurized oil through an intake passage and a discharge passage in the housing H, and again sucks up the oil that has flowed through the engine body 1 a and returned to the oil pan 1 c and circulates the same, as indicated by the double-stranded line.

The pump device M includes a housing body 10 and a housing cover 20 as the housing H, an inner rotor 30 and an outer rotor 40 as a pump element Pe, screws b for fastening the housing cover 20 to the housing body 10, and a cover member 50, as shown in FIG. 2 to FIG. 5 .

The housing body 10 is formed in a bottomed recessed shape opened on one side in the axis S direction using a metal material such as steel, cast iron, sintered steel, or aluminum alloy, that is, opened vertically upward in a use state applied to the outboard motor A.

The housing body 10 includes an outer wall surface 10 a; a cylindrical portion 11 defining a part of the outer wall surface 10 a and protruding downward around the axis S; a joint surface 12; a pump housing recess 13; an intake passage 14; a discharge passage 15; six screw holes 16 a and four through holes 16 b open to the joint surface 12, as shown in FIGS. 5 and 7 .

The cylindrical portion 11 defines an insertion hole 11 a on the axis S, and includes an outer peripheral surface 11 b, an end surface 11 c continuous with a lower end of the outer peripheral surface 11 b, and an annular recess 11 d formed further inward in the axis S direction than the insertion hole 11 a. Here, the outer peripheral surface 11 b and the end surface 11 c form a part of the outer wall surface 10 a of the housing body 10.

The insertion hole 11 a is formed as a circular hole centered on the axis S such that the drive shaft 3 may be inserted.

The annular recess 11 d defines a fitting inner peripheral surface 11 d ₁ centered on the axis S, and a thrust receiving surface 11 d ₂ perpendicular to the axis S direction, as shown in FIG. 6 . Two small-diameter seal members Sr₁ as annular seal members are stacked and fitted in the annular recess 11 d to be in close contact with the fitting inner peripheral surface 11 d ₁ and the thrust receiving surface 11 d ₂. The small-diameter seal member Sr₁ is in close contact with an outer peripheral surface 3 a of the drive shaft 3 inserted from the insertion hole 11 a, and is, for example, a lip seal (oil seal).

The joint surface 12 forms a flat surface perpendicular to the axis S such that a joint surface 22 of the housing cover 20 is joined from the axis S direction, as shown in FIG. 4 and FIG. 7 . Moreover, on the joint surface 12, two positioning pins P for positioning the housing cover 20 are fitted in a region around the pump housing recess 13, and an annular seal groove 12 a for arranging a seal member Gr is formed.

Here, a seal member molded of a liquid sealing agent or rubber and the like is used as the seal member Gr,

The pump housing recess 13 is a region for housing the pump element Pe (inner rotor 30 and outer rotor 40), and includes a small-diameter inner peripheral surface 13 a, a thrust surface 13 b, a large diameter inner peripheral surface 13 c, and an annular recess 13 d, as shown in FIG. 4 , FIG. 6 , and FIG. 7 .

The small-diameter inner peripheral surface 13 a receives a cylindrical portion 30 a of the inner rotor 30 to be rotatable around the axis S.

The thrust surface 13 b receives a one end surface 31 and a one end surface 41 of the inner rotor 30 and the outer rotor 40 in the axis S direction.

The large diameter inner peripheral surface 13 c supports an outer peripheral surface 43 of the outer rotor 40 rotatably around an axis S1 parallel to the axis S.

The annular recess 13 d is formed closer to the insertion hole 11 a than the small-diameter inner peripheral surface 13 a in the axis S direction, and defines a fitting inner peripheral surface 13 d ₁ centered on the axis S and a thrust receiving surface 13 d ₂ perpendicular to the axis S, as shown in FIG. 6 . A large diameter seal member Sr₂ as a second annular seal member is fitted in the annular recess 13 d to be in close contact with the fitting inner peripheral surface 13 d ₁ and the thrust receiving surface 13 d ₂. The large diameter seal member Sr₂ is in close contact with an outer peripheral surface 1 b ₁ of the crankshaft 1 b inserted from an insertion hole 21 of the housing cover 20, and is, for example, a lip seal (oil seal).

In other words, the second annular seal member (large diameter seal member Sr₂) is disposed in a region between the pump element Pe and the annular seal member (small-diameter seal member Sr₁) in the axis S direction to be in close contact with the outer peripheral surface 1 b ₁ of the crankshaft 1 b.

The intake passage 14 is formed as a grooved passage having a substantially rectangular cross-section and opened vertically upward in a use state applied to the outboard motor A, and extends horizontally, from an intake port 14 a defined at its upstream end and opened vertically downward, to a pump chamber intake port 14 b of the pump housing recess 13.

The discharge passage 15 is formed as a grooved passage having a substantially rectangular cross-section and opened vertically upward in a use state applied to the outboard motor A, and extends horizontally from its downstream end (a position facing a discharge port 25 a formed in the housing cover 20 and opened vertically upward) to a pump chamber discharge port 15 b facing the pump housing recess 13.

The six screw holes 16 a are for screwing the screws b that join the housing cover 20 to the housing body 10 in a region around the pump housing recess 13 and a region of the joint surface 12.

The four through holes 16 b pass bolts (not shown) for connecting the housing H (housing body 10 and housing cover 20) to the engine body 1 a in the region of the joint surface 12.

The housing cover 20 is coupled to the housing body 10 to close the housing body 10, and is formed into a bottomed recessed shape opened to the other side in the axis S direction using a material such as steel, cast iron, sintered steel, or aluminum alloy, that is, opened vertically downward in a use state applied to the outboard motor A.

The housing cover 20 has an insertion hole 21, the joint surface 22, an intake passage 24, a discharge passage 25, six circular holes 26 a, and four through holes 26 b as shown in FIG. 4 and FIG. 5 .

The insertion hole 21 is formed as a circular hole centered on the axis S such that a lower end connection portion of the crankshaft 1 b may be inserted.

The joint surface 22 forms a flat surface perpendicular to the axis S to be joined from the axis S direction to the joint surface 12 of the housing body 10, as shown in FIG. 5 . Moreover, the joint surface 22 is formed with two positioning holes h for fitting the positioning pins P of the housing body 10 in a region opposed around the pump housing recess 13. Furthermore, the joint surface 22 defines a thrust surface 22 a that receives the other end surfaces 32, 42 of the inner rotor and the outer rotor 40 in the region around the insertion hole 21.

The intake passage 24 is formed as a grooved passage having a substantially rectangular cross-section and opened vertically downward in a use state applied to the outboard motor A, and extends horizontally, from its upstream end (a position facing the intake port 14 a formed in the housing body 10 and opened vertically downward), to a pump chamber intake port 24 b facing the pump housing recess 13 of the housing body 10.

The discharge passage 25 is formed as a grooved passage having a substantially rectangular cross-section and opened vertically downward in a use state applied to the outboard motor A, and extends horizontally from the discharge port 25 a defined at its downstream end and opens vertically upward, to a pump chamber discharge port 25 b facing the pump housing recess 13.

The six circular holes 26 a are formed to pass the screws b that connect the housing cover to the housing body 10 in a region facing the pump housing recess 13 and a region of the joint surface 22.

The four through holes 26 b pass bolts (not shown) for connecting the housing H (housing body 10 and housing cover 20) to the engine body 1 a in the region of the joint surface 22.

The pump element Pe is arranged in the pump housing recess 13 of the housing body 10, and defines a pump chamber expanding and contracting to perform pumping action including suction processes, pressurizing processes, and discharge processes to oil, as shown in FIG. 4 to FIG. 6 . Here, the inner rotor 30 and the outer rotor 40 are trochoid rotors having trochoidal tooth shapes.

The inner rotor 30 is formed as an external gear having a tooth shape formed by a trochoid curve from a metal material such as steel or sintered steel, and includes the cylindrical portion 30 a that protrudes in the axis S direction to be fitted to the small-diameter inner peripheral surface 13 a; the one end surface 31 that slides the thrust surface 13 b of the housing body 10; the other end surface 32 that slides the thrust surface 22 a of the housing cover 20; and a fitting hole 33 into which the lower end connection portion of the crankshaft 1 b is fitted. The inner rotor 30 rotates integrally with the crankshaft 1 b in the direction of an arrow R around the axis S, as shown in FIG. 4 .

The outer rotor 40 is formed as an inner gear having a tooth shape that may be engaged with the inner rotor 30 from a metal material such as steel or sintered steel, and includes the one end surface 41 that slides the thrust surface 13 b of the housing body 10; the other end surface 42 that slides the thrust surface 22 a of the housing cover 20; and the cylindrical outer peripheral surface 43 centered on the axis S1. The outer peripheral surface 43 slidably contacts the large diameter inner peripheral surface 13 c of the housing body 10.

The outer rotor 40 rotates in the same direction as the inner rotor 30 around the axis S1 at a slower speed than the inner rotor 30 while interlocking with the rotation of the inner rotor 30 rotating around the axis S.

As the inner rotor 30 and the outer rotor 40 are partially engaged with each other to rotate, a pump chamber that expands and contracts is defined therebetween, and pumping action including a suction stroke, a pressurizing stroke, and a discharge stroke is continuously generated.

The cover member 50 is fixed to the housing H (housing body 10) to cover a region including the insertion hole 11 a into which the drive shaft 3 is inserted and a region exposed from the oil pan 1 c in the housing H (housing body 10), as shown in FIG. 6 .

In other words, the housing H (housing body 10) is formed to include an annular close contact region Ca in which a flange portion 1 c ₁ of the oil pan 1 c is in annular close contact such that the outer wall surface 10 a outside the region covered by the cover member 50 is disposed inside the oil pan 1 c included in the outboard motor A.

The cover member 50 is formed of a resin material excellent in heat resistance, water resistance and impact resistance, such as a polyamide resin material, into a bottomed cylindrical shape (a cap shape), as shown in FIGS. 3, 6, 8 and 9 , and includes an annular flange portion 51, an outer peripheral wall portion 52, a bottom wall portion 53 and a tip cylindrical portion 54.

The annular flange portion 51 forms an annular flat surface perpendicular to the axis S to come into annular close contact with the outer wall surface 10 a around a root of the cylindrical portion 11 of the housing body 10.

The outer peripheral wall portion 52 forms a cylindrical wall to cover the outer peripheral surface 11 b of the cylindrical portion 11 of the housing body 10.

Moreover, a plurality of (12 in this case) of linear protruding portions 52 a extending in the axis S direction and arranged at equal intervals around the axis S are formed on an inner peripheral surface of the outer peripheral wall portion 52.

The plurality of linear protruding portions 52 a are formed to have a height dimension such that the outer peripheral wall portion 52 of the cover member 50 is press-fitted to (the outer peripheral surface 11 b of) the cylindrical portion 11. Here, the height dimension is a protrusion amount in which the plurality of linear protruding portions 52 a protrude from the inner peripheral surface inward in the radial direction perpendicular to the axis S.

The bottom wall portion 53 forms a flat surface perpendicular to the axis S at a tip (lower end) of the outer peripheral wall portion 52 to cover the end surface 11 c of the cylindrical portion 11 of the housing body 10. Moreover, on an inner surface of the bottom wall portion 53, an annular protrusion portion 53 a that annularly abuts on the end surface 11 c of the cylindrical portion 11 is formed.

When the cover member 50 is fitted to the cylindrical portion 11, pressure on a contact surface of the annular protrusion portion 53 a with the end surface 11 c of increases, and thus sealing performance can be improved.

The tip cylindrical portion 54 extends from the bottom wall portion 53 outward (downward) in the axis S direction over a predetermined length L, and defines a small-diameter insertion hole 54 a into which the drive shaft 3 is rotatably inserted.

The small-diameter insertion hole 54 a is a circular hole centered on the axis S, and has an inner diameter smaller than the insertion hole 11 a of the housing body 10. In other words, the small-diameter insertion hole 54 a is formed to have an inner diameter dimension allowing the rotation of the drive shaft 3 at a small gap from the outer peripheral surface 3 a of the drive shaft 3. Here, the “small gap” is a gap that is not in contact with the outer peripheral surface 3 a of the drive shaft 3, and seawater or seawater droplets and the like cannot enter.

In the tip cylindrical portion 54, since the small-diameter insertion hole 54 a forming a small gap with the outer peripheral surface 3 a of the drive shaft 3 is formed over the predetermined length L, a region of the small gap may be set longer in the axis S direction as compared with the case where the small-diameter insertion hole is formed by a thickness of the bottom wall portion 53. Thus, the passage resistance between the small-diameter insertion hole 54 a and the drive shaft 3 can be increased, and seawater droplets or seawater and the like about to intrude the inside of the housing body 10 can be effectively blocked.

Then, an operation of assembling the pump device M configured as above will be described.

When assembled, the housing H (housing body 10, housing cover 20), the pump element Pe (inner rotor 30 and outer rotor 40), the two small-diameter seal members Sr₁, the large diameter seal member Sr₂, the cover member 50, the two positioning pins P, six screws b, and the seal member Gr are prepared.

First, the two positioning pins P, the two small-diameter seal members Sr₁, the large diameter seal member Sr₂, and the pump element Pe are assembled to the housing body 10. To be specific, the two positioning pins P are fitted into fitting holes on the joint surface 12, the two small-diameter seal members Sr₁ are fitted into the annular recess 11 d, the large diameter seal member Sr₂ is fitted into the annular recess 13 d, and the pump element Pe is incorporated within the pump housing recess 13.

Next, the seal member Gr is applied or arranged on the joint surface 12, and the housing cover 20 is assembled to the housing body 10.

To be specific, the housing cover 20 is joined to the housing body 10 from the axis S direction and the six screws b are screwed into the screw holes 16 a through the circular holes 26 a such that the positioning pins P are fitted into the positioning holes h and the joint surface 22 is joined to the joint surface 12.

Finally, the cover member 50 is assembled to the cylindrical portion 11 defining the insertion hole 11 a of the housing body 10 which constitutes the housing H by approaching it from the outside in the axis S direction. To be specific, the cover member 50 is press-fitted to the housing H (the cylindrical portion 11 of the housing body 10) such that the annular flange portion 51 comes into annular close contact with the outer wall surface 10 a around the root of the cylindrical portion 11, the plurality of linear protruding portions 52 a of the outer peripheral wall portion 52 come into close contact with the outer peripheral surface 11 b of the cylindrical portion 11, and the annular protrusion portion 53 a of the bottom wall portion 53 comes into close contact with the end surface 11 c of the cylindrical portion 11.

Thus, the cover member 50 is fixed to the housing H, and assembling of the pump device M is completed. The assembly procedure is not limited to the above, and other procedures may be used.

As described above, the resin cover member 50 is fixed to cover the outer wall surface 10 a of the housing H in the region including the insertion hole 11 a, it is possible to achieve cost reduction, simplification of structure, and the like without performing expensive rust prevention treatment, prevent salt damage due to exposure to seawater atmosphere, and ensure functional reliability.

Here, since the cover member 50 has the small-diameter insertion hole 54 a having an inner diameter smaller than the insertion hole 11 a of the housing H for allowing the drive shaft 3 to rotate through, the resistance of the flow path leading into the housing H is increased, and it is possible to prevent seawater droplets or seawater and the like from intruding, and prevent salt damage such as rust or malfunction due to rust compared with the case where only the insertion hole 11 a is used.

Further, since the housing H includes, as a convex cylindrical portion, the cylindrical portion 11 that protrudes outward (downwards) cylindrically around the axis S of the drive shaft 3 to define the insertion hole 11 a, and the cover member 50 includes the annular flange portion 51 in close contact with the outer wall surface 10 a around the root of the cylindrical portion 11; the outer peripheral wall portion 52 that covers the outer peripheral surface 11 b of the cylindrical portion 11; the bottom wall portion 53 that covers the end surface 11 c of the cylindrical portion 11; and the tip cylindrical portion 54 extending from the bottom wall portion 53 outward (downward) in the axis S direction and defining the small-diameter insertion hole 54 a, the housing H and the cover member 50 can be formed in a simple form, thereby contributing to the simplification of the structure.

As shown in FIG. 10 , since the cover member 50 includes the annular protrusion portion 53 a that annularly abuts on the end surface 11 c of the cylindrical portion 11 in the bottom wall portion 53, contact surface pressure between the bottom wall portion 53 and the end surface 11 c can be increased, and seawater droplets or seawater and the like about to intrude between the bottom wall portion 53 and the end surface 11 c can be efficiently blocked.

Moreover, since the cover member 50 extends in the axis S direction to be in close contact with the outer peripheral surface 11 b of the cylindrical portion 11 in the outer peripheral wall portion 52, and includes the plurality of linear protruding portions 52 a arranged around the axis S, contact surface pressure between the outer peripheral wall portion 52 and the outer peripheral surface 11 b can be increased. In particular, since the plurality of linear protruding portions 52 a are formed to have a height dimension such that the cover member 50 is press-fitted to the cylindrical portion 11 of the housing H, the cover member 50 can be easily fixed to the housing H by press-fitting.

As shown in FIG. 6 , since the housing H includes a second annular seal member (large diameter seal member Sr₂) disposed to be in close contact with the outer peripheral surface 1 b ₁ of the crankshaft 1 b in a region between the pump element Pe and the annular seal member Sr₁ in the axis S direction, oil can be prevented from flowing along the crankshaft 1 b and flowing out toward the insertion hole 11 a.

On the other hand, since the annular seal members (two small-diameter seal members Sr₁) are disposed on the side close to the insertion hole 11 a in the housing H, even if seawater or seawater droplets and the like intrudes from the insertion hole 11 a, the intruding matter can be reliably blocked by the annular seal members (two small-diameter seal members Sr₁).

Here, since the cover member 50 is disposed further outside the annular seal members (two small-diameter seal members Sr₁), intrusion of seawater or seawater droplets and the like can be reliably prevented outside the insertion hole 11 a.

Next, pumping operation of the pump device M in the outboard motor A will be briefly described.

When the crankshaft 1 b is rotated by starting the engine 1, the drive shaft 3 is rotated, and the propeller 4 is rotated through a transmission mechanism.

Moreover, the pump device M is started by the rotation of the crankshaft 1 b. To be specific, the inner rotor 30 rotates in the direction of the arrow R, the outer rotor 40 rotates interlocked in the same direction, and the pumping action is generated by the enlargement and contraction of the pump chamber.

The oil sucked up from the intake port 14 a through the oil strainer 1 d flows in the intake passages 14, 24 and is sucked into the pump chamber from the pump chamber intake ports 14 b, 24 b arranged on two end surfaces of the pump element Pe. Next, due to the pumping action of the pump element Pe, the pressurized oil is discharged from discharge ports 25 a, from the pump chamber discharge ports 15 b, 25 b arranged on the two end surfaces of the pump element Pe through the discharge passages 15, 25, and supplied to a supply destination in the engine 1. The oil supplied into the engine 1 is returned again to the oil pan 1 c from a predetermined discharge port after passing through locations necessary for lubrication. After that, the oil in the oil pan 1 c is sucked up again by the pump device M and circulated.

According to the pump device M configured as the above, it is possible to achieve cost reduction, simplification of structure, and the like without performing expensive rust prevention treatment, prevent salt damage and the like, and ensure functional reliability. Therefore, according to the outboard motor A including the pump device M, salt damage and the like does not occur, and the pump device M also surely operates, thus functional reliability of the engine 1 for rotationally driving the drive shaft 3 can be secured.

FIG. 11 to FIG. 13 show a cover member 150 related to a second embodiment, and the same configuration as the cover member 50 related to the first embodiment is given the same reference numeral and the description is omitted.

The cover member 150 of the second embodiment is formed in a bottomed cylindrical shape (cap shape) using the same resin material as above, and includes the annular flange portion 51, the outer peripheral wall portion 52, the bottom wall portion 53, and an inner cylindrical portion 154.

The inner cylindrical portion 154 extends from the bottom wall portion 53 inward (upward) in the axis S direction over a predetermined length L1, and defines a small-diameter insertion hole 154 a closely fitted to the insertion hole 11 a and into which the drive shaft 3 is rotatably inserted.

The small-diameter insertion hole 154 a is a circular hole centered on the axis S, and has an inner diameter smaller than the insertion hole 11 a of the housing body 10. In other words, the small-diameter insertion hole 154 a is formed to have an inner diameter dimension allowing the rotation of the drive shaft 3 at a small gap from the outer peripheral surface 3 a of the drive shaft 3.

In the inner cylindrical portion 154, since the small-diameter insertion hole 154 a forming a small gap with the outer peripheral surface 3 a of the drive shaft 3 is formed over the predetermined length L1, the region of the small gap may be set longer in the axis S direction as compared with the case where the small-diameter insertion hole is formed by the thickness of the bottom wall portion 53. Thus, the passage resistance between the small-diameter insertion hole 154 a and the drive shaft 3 can be increased, and seawater droplets or seawater and the like about to intrude the inside of the housing body 10 can be effectively blocked.

Further, since the inner cylindrical portion 154 is closely fitted to the insertion hole 11 a as shown in FIG. 13 , the insertion hole 11 a can be reliably covered and the outer peripheral wall portion 52 and the inner cylindrical portion 154 are arranged in cooperation to sandwich the cylindrical portion 11 in the radial direction.

In other words, when the cover member 150 is fitted to the cylindrical portion 11 of the housing H, the plurality of linear protruding portions 52 a of the outer peripheral wall portion 52 are in close contact with the outer peripheral surface 11 b, and the inner cylindrical portion 154 is in close contact with the insertion hole 11 a, thus the cover member 150 can be more firmly press-fitted and fixed to the cylindrical portion 11.

The other action effect of the cover member 150 is the same as that of the cover member 50.

FIG. 14 to FIG. 16 show a cover member 250 related to a third embodiment, and the same configuration as the cover member 50 related to the first embodiment is given the same reference numeral and the description is omitted.

The cover member 250 according to the third embodiment is formed in a bottomed cylindrical shape (cap shape) using the same resin material as above, and includes the annular flange portion 51, the outer peripheral wall portion 52, the bottom wall portion 53, and a long cylindrical portion 254 that penetrates the bottom wall portion 53 in the axis S direction.

The long cylindrical portion 254 is configured to include both the tip cylindrical portion 54 and the inner cylindrical portion 154, and extend from the bottom wall portion 53 outward (downward) in the axis S direction over the predetermined length L to be closely fitted to the insertion hole 11 a and extends from the bottom wall portion 53 inward (upward) in the axis S direction over the predetermined length L1 to define a small-diameter insertion hole 254 a into which the drive shaft 3 is rotatably inserted.

The small-diameter insertion hole 254 a is a circular hole centered on the axis S, and has an inner diameter smaller than the insertion hole 11 a of the housing body 10. In other words, the small-diameter insertion hole 254 a is formed to have an inner diameter dimension allowing the rotation of the drive shaft 3 at a small gap from the outer peripheral surface 3 a of the drive shaft 3.

In the long cylindrical portion 254, since the small-diameter insertion hole 254 a forming the small gap with the outer peripheral surface 3 a of the drive shaft 3 is formed over a predetermined length L2 (=L+L1+thickness), the region of the small gap may be set longer in the axis S direction as compared with the case where the small-diameter insertion hole is formed by the thickness of the bottom wall portion 53. Thus, the passage resistance between the small-diameter insertion hole 254 a and the drive shaft 3 can be increased, and seawater droplets or seawater and the like about to intrude the inside of the housing body 10 can be effectively blocked.

Further, since the long cylindrical portion 254 is closely fitted into the insertion hole 11 a as shown in FIG. 16 , the insertion hole 11 a can be reliably covered and the outer peripheral wall portion 52 and the long cylindrical portion 254 are arranged in cooperation to sandwich the cylindrical portion 11 in the radial direction.

Therefore, the cover member 250, similar to the cover member 150, can be more firmly press-fitted and fixed to the cylindrical portion 11.

The other action effect of the cover member 250 is the same as that of the cover member 50.

FIG. 17 to FIG. 19 show a cover member 350 related to a fourth embodiment, and the same configuration as the cover member 50 related to the first embodiment is given the same reference numeral and the description is omitted.

The cover member 350 according to the fourth embodiment is formed in a bottomed cylindrical shape (cap shape) using the same resin material as above, and includes the annular flange portion 51, the outer peripheral wall portion 52, the bottom wall portion 53, and a tip cylindrical portion 354.

The tip cylindrical portion 354 extends from the bottom wall portion 53 outward (downward) in the axis S direction over the predetermined length L, and defines a small-diameter insertion hole 354 a into which the drive shaft 3 is rotatably inserted.

The small-diameter insertion hole 354 a has a circular hole centered on the axis S and is formed with a spiral protruding portion having unevenness formed on the inner wall surface, and an inner diameter of a protruding portion is smaller than the insertion hole 11 a of the housing body 10. In other words, the small-diameter insertion hole 354 a is formed to have an inner diameter dimension allowing the rotation of the drive shaft 3 at a small gap from the outer peripheral surface 3 a of the drive shaft 3.

In the tip cylindrical portion 354, since the small-diameter insertion hole 354 a formed as the spiral protruding portion to form a small gap with the outer peripheral surface 3 a of the drive shaft 3 is formed over the predetermined length L, the region of the small gap may be set longer in the axis S direction as compared with the case where the small-diameter insertion hole is formed by the thickness of the bottom wall portion 53.

Thus, the passage resistance between the small-diameter insertion hole 354 a and the drive shaft 3 can be increased, and seawater droplets or seawater and the like about to intrude the inside of the housing body 10 can be effectively blocked. In particular, since the inner wall surface of the small-diameter insertion hole 354 a is formed as a spiral protruding portion, it has a labyrinth structure in which the passage of the gap from the outer peripheral surface 3 a of the drive shaft 3 repeatedly contracts and expands. Thereby, the kinetic energy of the seawater or seawater droplets and the like about to intrude can be absorbed, and the intrusion can be efficiently prevented.

In particular, since the small-diameter insertion hole 354 a is formed spirally, feed screw action of the spiral protruding portion is generated by relative rotational movement of the small-diameter insertion hole 354 a (spiral protruding portion) and the drive shaft 3, and even if seawater and the like intrudes into the small-diameter insertion hole 354 a, it can be sent downward in the axis S direction.

In the embodiment, the cover members 50, 150, 250, 350 covering regions including a convex cylindrical portion (cylindrical portion 11) of the housing H are shown as the cover members, but the disclosure is not limited thereto; other forms of cover members may be used as long as they cover the outer wall surface of the housing in the region including an insertion hole into which the drive shaft 3 is inserted.

For example, in a configuration in which a cover member includes an annular flange portion in close contact with an outer wall surface around a root of a cylindrical portion of a housing, an outer peripheral wall portion covering an outer peripheral surface of the cylindrical portion, and a bottom wall portion covering an end surface of the cylindrical portion, the bottom wall portion may be configured to define a small-diameter insertion hole.

In the embodiment, the cylindrical portion 11 that protrudes cylindrically around the axis S is shown as the convex cylindrical portion of the housing, but the disclosure is not limited thereto; a polygonal (for example, hexagonal) convex cylindrical portion or other-shaped convex cylindrical portion may be employed as long as it is covered with a cover member and the cover member can be fixed to the housing.

In the embodiment, the tip cylindrical portion 354 of the cover member 350 configured to include a spiral protruding portion formed spirally around the axis S to define the small-diameter insertion hole 354 a is shown, but the disclosure is not limited thereto; the small-diameter insertion hole 154 a of the inner cylindrical portion 154 of the cover member 150 may be configured to include the spiral protruding portion, or the small-diameter insertion hole 254 a of the long cylindrical portion 254 of the cover member 250 may be configured to include a spiral protruding portion.

In the embodiment, the cover members 50, 150, 250, 350 fixed to the housing H by press-fitting are shown, but the disclosure is not limited thereto; a cover member that is fixed by adopting a snap fit structure, a bayonet structure and the like may be adopted as long as the cover member can be fixed to the housing.

As described above, according to the pump device of the disclosure, it is possible to achieve cost reduction, simplification of structure, and the like without performing expensive rust prevention treatment, prevent salt damage and the like, and ensure functional reliability. Thus, it is applicable not only to engines mounted on outboard motors, but also to other engines, oil and other fluid circulation devices, and the like where intrusion of foreign matter from an insertion hole is a concern. 

What is claimed is:
 1. A pump device to be applied to an outboard motor, comprising: a housing that has an insertion hole into which a drive shaft driven by an engine is to be inserted, and a resin cover member that is fixed to the housing to cover an outer wall surface of the housing in a region having the insertion hole, wherein the cover member has a small-diameter insertion hole having an inner diameter smaller than the insertion hole to allow the drive shaft to be rotatably inserted thereto.
 2. The pump device according to claim 1, wherein the housing comprises a convex cylindrical portion that protrudes in an axial direction of the drive shaft to define a part of the insertion hole and the outer wall surface, and the cover member is formed to cover a region comprising the convex cylindrical portion.
 3. The pump device according to claim 2, wherein the convex cylindrical portion is a cylindrical portion that protrudes cylindrically around an axis of the drive shaft, and the cover member comprises an annular flange portion in close contact with an outer wall surface around a root of the cylindrical portion; an outer peripheral wall portion that covers an outer peripheral surface of the cylindrical portion; and a bottom wall portion that covers an end surface of the cylindrical portion and defines the small-diameter insertion hole.
 4. The pump device according to claim 2, wherein the convex cylindrical portion is a cylindrical portion that protrudes cylindrically around an axis of the drive shaft, and the cover member comprises an annular flange portion in close contact with an outer wall surface around a root of the cylindrical portion; an outer peripheral wall portion that covers an outer peripheral surface of the cylindrical portion; a bottom wall portion that covers an end surface of the cylindrical portion; and an inner cylindrical portion that extends from the bottom wall portion inward in the axial direction to be closely fitted to the insertion hole and defines the small-diameter insertion hole.
 5. The pump device according to claim 4, wherein the inner cylindrical portion comprises a spiral protruding portion formed spirally around the axis to define the small-diameter insertion hole.
 6. The pump device according to claim 2, wherein the convex cylindrical portion is a cylindrical portion that protrudes cylindrically around an axis of the drive shaft, and the cover member comprises an annular flange portion in close contact with an outer wall surface around a root of the cylindrical portion; an outer peripheral wall portion that covers an outer peripheral surface of the cylindrical portion; a bottom wall portion that covers an end surface of the cylindrical portion; and a tip cylindrical portion that extends from the bottom wall portion outward in the axial direction to define the small-diameter insertion hole.
 7. The pump device according to claim 6, wherein the tip cylindrical portion comprises a spiral protruding portion formed spirally around the axis to define the small-diameter insertion hole.
 8. The pump device according to claim 2, wherein the convex cylindrical portion is a cylindrical portion that protrudes cylindrically around an axis of the drive shaft, and the cover member comprises an annular flange portion in close contact with an outer wall surface around a root of the cylindrical portion; an outer peripheral wall portion that covers an outer peripheral surface of the cylindrical portion; a bottom wall portion that covers an end surface of the cylindrical portion; and a long cylindrical portion that extends from the bottom wall portion inward in the axial direction to be closely fitted to the insertion hole and extends outward in the axial direction to define the small-diameter insertion hole.
 9. The pump device according to claim 8, wherein the long cylindrical portion comprises a spiral protruding portion formed spirally around the axis to define the small-diameter insertion hole.
 10. The pump device according to claim 3, wherein the cover member comprises, in the bottom wall portion, an annular protrusion portion that annularly abuts on the end surface of the cylindrical portion.
 11. The pump device according to claim 3, wherein the cover member comprises, in the outer peripheral wall portion, a plurality of linear protruding portions that extend in the axial direction to come into close contact with the outer peripheral surface of the cylindrical portion and arranged around the axis.
 12. The pump device according to claim 11, wherein the plurality of linear protruding portions are formed to have a height dimension with which the cover member is press-fitted to the cylindrical portion of the housing.
 13. The pump device according to claim 1, comprising: a pump element housed in the housing, wherein the pump element comprises an inner rotor connected to a crankshaft of the engine and driven to rotate, and an outer rotor interlocked with the inner rotor.
 14. The pump device according to claim 13, wherein the housing comprises an annular seal member disposed inside the cylindrical portion to be in close contact with an outer peripheral surface of the drive shaft inserted from the insertion hole and connected to the crankshaft.
 15. The pump device according to claim 13, wherein the housing comprises a second annular seal member arranged to come into close contact with an outer peripheral surface of the crankshaft in a region between the pump element and the annular seal member in the axial direction.
 16. The pump device according to claim 14, wherein the housing comprises a second annular seal member arranged to come into close contact with an outer peripheral surface of the crankshaft in a region between the pump element and the annular seal member in the axial direction.
 17. The pump device according to claim 1, wherein the housing comprises an annular close contact region in which a flange portion of an oil pan is in annular close contact such that an outer wall surface outside a region covered by the cover member is arranged inside the oil pan comprised in the outboard motor.
 18. An outboard motor, comprising: an engine that comprises an engine body, a crankshaft that extends vertically in the engine body, an oil pan fixed to the engine body and storing oil, and a pump device fixed to the engine body and circulating the oil; a body that holds the engine; a drive shaft that is connected to the crankshaft and that rotates around an axis extending vertically, and a propeller rotated by the drive shaft, wherein the pump device is the pump device according to claim
 1. 